1. Field of the Invention
The present invention relates to a method, apparatus and program for measuring an electric-field vector, electromagnetic-field vector and distant electromagnetic-field intensity of an electromagnetic field formed by an electromagnetic wave radiated, for example, from an appliance, and to a medium storing the program.
2. Description of the Related Technology
Recently, the electromagnetic wave radiated from an appliance is particularly problematic. The industrial associations have the standards regulating radiant electromagnetic wave intensity permitted. In an effort to reduce the unwanted radiant electromagnetic waves, appliance manufacturers have taken various measures (EMC measures) in the development. It is necessary to perform a measurement of the intensity of an electromagnetic filed located nearly several meters away from an object-to-be-measured within an open site or radio darkroom, in order to confirm whether the electronic appliance concerned satisfies the standard.
However, such an open site or radio darkroom requires equipments great in scale and thus vast investment. Besides, for each measurement, the object-to-be-measured must be inconveniently carried into an open site or radio darkroom. This increases the cost of the development of an electronic appliance.
In order to solve the problem, there is conventionally a structure having a scanning magnetic-field sensor to scan on each of measurement positions established in a space surrounding an object-to-be-measured, and a fixed magnetic-field sensor fixedly arranged near the object-to-be-measured, thereby calculating a distribution of magnetic-field intensity, direction and phase from detected signals by both sensors and determining a distant electromagnetic-field intensity from the magnetic-field intensity, direction and phase thus calculated (see JP-A-2004-69372, for example).
However, the existing method has its own limitation. Where a loop antenna is used as a scanning magnetic-field sensor for example, the scanning interval of the sensor and the size of the whole structure are still too big because of the relatively large size of the antenna's loop area.
Meanwhile, the intensity of electromagnetic field at a distance from an object-to-be-measured can be determined from a distribution of magnetic-field intensities, directions and phases at a scanning position. However, because of the incapability of knowing the distribution of electric-field intensities, directions and phases on the scanning plane, it is impossible to grasp the direction of an electromagnetic wave actually radiated from the electronic appliance. Thus, the EMC measure is limited in respect of the effect upon the electronic appliance.
Meanwhile, where using an electric-field sensor or electromagnetic-field sensor in place of the magnetic-field sensor, the existing method is merely to measure an electric-field intensity, etc. vertical to the scanning plane on a measuring-position basis, wherein the intensity, direction and phase of electric field is unknown over the scanning plane as to the electronic appliance.